linux-kernel - Re: [PATCH] platform/x86/intel: power-domains validate domain in tpmi_cpu

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Message-ID: <00466c7a41bd4a0120a7798318ac5bba8878ada5.camel@linux.intel.com>
Date: Tue, 26 Aug 2025 13:26:46 -0700
From: srinivas pandruvada <srinivas.pandruvada@...ux.intel.com>
To: David Arcari <darcari@...hat.com>, platform-driver-x86@...r.kernel.org
Cc: Hans de Goede <hansg@...nel.org>, Ilpo Järvinen
 <ilpo.jarvinen@...ux.intel.com>, Peter Zijlstra <peterz@...radead.org>,
 Ingo Molnar <mingo@...nel.org>, Dan Carpenter <dan.carpenter@...aro.org>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Tero Kristo
 <tero.kristo@...ux.intel.com>,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] platform/x86/intel: power-domains validate domain in
 tpmi_cpu_online()

Hi David,

On Tue, 2025-08-26 at 12:43 -0400, David Arcari wrote:
> Although tpmi_get_power_domain_mask() calls tpmi_domain_is_valid()
> prior to indexing tpmi_power_domain_mask[],
Because this an API call so that caller parameter needs to be
sanitized.

>  tpmi_cpu_online() does
> not.
This is hotplug callback, which should have correct topology
information.

>  In the case where a VM creates non-contiguous package ids the
> result can be memory corruption. This can be prevented by adding
> the same validation in tpmi_cpu_online().
> 

This driver is getting loaded means MSR 0x54 is virtualised otherwise
this driver will not load.
Not sure this is an upstream kernel or not.

Some comments below.

> Fixes: 17ca2780458c ("platform/x86/intel: TPMI domain id and CPU
> mapping")
> 
Andy already pointed about new line here.

> Cc: Hans de Goede <hansg@...nel.org>
> Cc: "Ilpo Järvinen" <ilpo.jarvinen@...ux.intel.com>
> Cc: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Dan Carpenter <dan.carpenter@...aro.org>
> Cc: David Arcari <darcari@...hat.com>
> Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Cc: Tero Kristo <tero.kristo@...ux.intel.com>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: David Arcari <darcari@...hat.com>
> ---
>  drivers/platform/x86/intel/tpmi_power_domains.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/platform/x86/intel/tpmi_power_domains.c
> b/drivers/platform/x86/intel/tpmi_power_domains.c
> index 9d8247bb9cfa..ae5b58679e29 100644
> --- a/drivers/platform/x86/intel/tpmi_power_domains.c
> +++ b/drivers/platform/x86/intel/tpmi_power_domains.c
> @@ -194,6 +194,9 @@ static int tpmi_cpu_online(unsigned int cpu)
>  	if (ret)
>  		return 0;
>  
Need some more information.

The only case this check is required if
topology_physical_package_id(cpu) is returning greater or equal to
topology_max_packages(). If this true in this case, please check the
value of info->pkg_id. If this is bad then then some other places also
this may have issue. info->punit_domain_id is already checked for valid
value in tpmi_get_logical_id().


Thanks,
Srinivas

> +	if (!tpmi_domain_is_valid(info))
> +		return 0;
> +
>  	index = info->pkg_id * MAX_POWER_DOMAINS + info-
> >punit_domain_id;
>  
>  	guard(mutex)(&tpmi_lock);